Toxicity Of PCB77 On Development Of Zebrafish Embryos

Polychlorinated biphenyl(PCB),as a globally distributed environmental pollutant,is the most representative of persistent organic pollutants,with long-term residual,bioaccumulative,highly toxic,long-distance Physical and chemical properties such as mobility,which have toxic effects on the body's immune,skin,reproductive,nervous and embryonic,heart,skeletal development systems.In recent years,as an aquatic animal,zebrafish has been gradually and extensively applied to the research on the development,function and disease of various organs of organisms with its unique biological advantages.Because of its small individual size,short oviposition cycle,high egg production,easy observation and manipulation during embryonic development,and it is genomically similar to humans,it can meet experimental studies of toxic organisms that require large sample sizes.It has been widely used in researches such as developmental biology and toxicology,and has also become one of the most popular vertebrate experimental models.Therefore,this study selected zebrafish embryos as the test organisms to systematically evaluate the toxicity and toxicity-sensitive phases of polychlorinated biphenyls on the development of zebrafish embryos in order to improve the toxicological data and systematic environmental risks of polychlorinated biphenyls.The evaluation provides a theoretical basis.In this study,different concentrations of PCB77 were used to infect zebrafish embryos.Survival,heart rate and hatching rate of zebrafish embryos and morphological malformations during development were observed and recorded.Further experiments were performed to record the developmental stages.The survival rate of zebrafish embryos exposed to PCB77 was calculated and the LD50 was calculated;the results showed that:1.A certain concentration of PCB77 exposure can cause the survival rate and hatching rate of zebrafish embryos to decrease.Within a certain concentration range,there is a significant dose-effect relationship between PCB77 concentration and the survival rate and hatching rate of zebrafish embryos.2.With the development and maturation of zebrafish embryos,its heart rate gradually increased.Exposure to certain concentrations of PCB77 can cause the heart rate of zebrafish embryos to decrease,and there is a clear dose-effect relationship between PCB77 concentration and heart rate.3.The teratogenic performance of zebrafish embryo development at different stages or different concentrations of PCB 77 exposure is not the same.At 4hpf,0.077mg/L PCB77 exposure concentration,the embryo showed more yolk convexity,0.2mg/L.Exposure to PCB 77 was mostly caused by egg condensation.At 120 hpf,the exposure of 0.008 mg/L of PCB 77 was revealed.The zebrafish embryos hatched from the embryos exhibited more curvature of the spine and 0.2 mg/L of PCB 77 exposure,most of which showed delayed incubation.4.At the same concentration of PCB 77,the survival time of the zebrafish embryos in the cleavage stage was the lowest at the same exposure time,while the survival rate of the zebrafish embryos in the gastrula stage was higher than that of the cleavage stage and the blastocyst stage.5.At the first 12 hours of exposure,zebrafish embryos were more sensitive to PCB 77 at 4 hpf than at 2 hpf.Over time,zebrafish embryos developed at 2 hpf compared to 4 hpf.PCB77 is more sensitive and has a certain time-effect relationship.